
<template>
  <div>
    <router-link 
      tag="div" 
      to="/" 
      class="header-abs"
      v-show="showAbs"
    >
      <div class="iconfont header-abs-black">&#xe624;</div>
    </router-link>
    <div 
      class="header-fixed" 
      v-show="!showAbs"
      :style="opacityStyle"  
    >
      <router-link to="/">
        <div class="iconfont header-fixed-black">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: "detailHeader",
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  //使用了keep-live标签后。每次进入页面都会执行
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  //使用了keep-live标签后。每次离开页面都会执行
  deactivated(){
    window.removeEventListener('scroll', this.handleScroll)
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if(top > 60 ) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1: opacity
        this.opacityStyle = {
          opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  }
}
</script>

<style lang="stylus" scoped>
 @import "~styles/varibles.styl"
  .header-abs
    position: absolute
    left: 0.2rem
    top: .2rem
    width: 0.8rem
    height: 0.8rem
    line-height: .8rem 
    border-radius: .4rem
    background: rgba(0,0,0,0.8)
    .header-abs-black
      color: #fff
      font-size: .4rem
      margin-left: .12rem
  .header-fixed
    z-index: 2
    position: fixed
    top: 0
    left: 0
    right: 0 
    height: $HeaderHeight
    line-height: $HeaderHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem 
    .header-fixed-black
      position: absolute
      left: 0
      top: 0 
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #fff  
</style>

